“I’m trying to come up with a good way of creating this in OpenSCAD… I have something using a bunch of hull’d cylinders but I’m wondering if there is a better/easier way to do it.” @rasterweb
A friend posted a design pondering whether there was a better way to design an object in OpenSCAD. As so often happens when I approach a 3D design, one solution pops up in my head… and is immediately discarded as garbage. That first thought was to create a negative of the interior of the spring, then iterate along the length of a stretched cube.
In the end, I opted for1 creating a flat version of a single “loop”, made from differenced hulled circles, repeated over the number of desired loops, then trimming alternating ends (so it wouldn’t look like a chain).
OpenSCAD spring by MakerBlock
Here’s the OpenSCAD code to produce this spring:2
// Settings
$fn = pow(2,6);
// Spring Dimensions
springH = 5;
springOD = 10;
springW = springOD*2;
springOR = springOD/2;
springTh = 2;
springIR = springOR-springTh;
loops = 8;
spring();
module spring()
{
linear_extrude(height=springH, center=false)
for (i=[0:loops])
{
translate([0,(springOD-springTh)*i,0])
difference()
{
spring_loop();
translate([-springOR+(springW+springOD)*(i%2),0,0])
square(springOD, center=true);
}
}
}
module spring_loop()
{
difference()
{
hull()
{
circle(r=springOR);
translate([springW,0,0])
circle(r=springOR);
}
hull()
{
circle(r=springIR);
translate([springW,0,0])
circle(r=springIR);
}
}
}
Some notes about my OpenSCAD style:
- I like to use OD/ID/OR/IR to mean outer diameter, inner diameter, outer radius, inner radius.
- I think the “spring_loop” module could be simplified slightly by calling another module which creates each hulled circle, but weighing the additional module code against just retyping a little code I opted for what got it done faster.
- I like to specify the facets on circular objects right at the top of the file. This way, I can adjust the smoothness of the object by just changing just the exponent part of the $fn system variable.
- Reasonably parametric. There’s some additional further optimization that could be done in the spring alternate end clipping.
Can’t wait to see what @rasterweb makes with a 3D printed spring!